US3934058A - Method of stabilizing the hot resistance of ceramic positive temperature coefficient resistors - Google Patents

Method of stabilizing the hot resistance of ceramic positive temperature coefficient resistors Download PDF

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Publication number
US3934058A
US3934058A US05/478,855 US47885574A US3934058A US 3934058 A US3934058 A US 3934058A US 47885574 A US47885574 A US 47885574A US 3934058 A US3934058 A US 3934058A
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Prior art keywords
temperature coefficient
positive temperature
resistor
resistors
indium
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Expired - Lifetime
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US05/478,855
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English (en)
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Baerbel Seebacher
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Siemens AG
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Siemens AG
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Priority claimed from DE19732330908 external-priority patent/DE2330908C3/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/30—Apparatus or processes specially adapted for manufacturing resistors adapted for baking
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/28—Apparatus or processes specially adapted for manufacturing resistors adapted for applying terminals
    • H01C17/281—Apparatus or processes specially adapted for manufacturing resistors adapted for applying terminals by thick film techniques
    • H01C17/283—Precursor compositions therefor, e.g. pastes, inks, glass frits
    • H01C17/286—Precursor compositions therefor, e.g. pastes, inks, glass frits applied to TiO2 or titanate resistors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49083—Heater type
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49085—Thermally variable
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49101—Applying terminal

Definitions

  • the present invention relates to ceramic positive temperature coefficient resistors and somewhat more particularly to a method of stabilizing the hot resistance of such resistors.
  • German Pat. No. 1,490,713 discloses ceramic positive temperature coefficient resistors having non-blocking heat applied contact coatings thereon. It is suggested therein that contact coatings be provided by applying a thin film of indium or indium-gallium onto a surface of the ceramic body, then applying a heatable silver preparation onto the thin film and then heating the resultant structure in an oxidizing atmosphere to adhere, burn-in or sinter the contact coatings onto the ceramic body.
  • the hot resistance of resistors composed of such materials attains only about 0.3 to 3% of the value such resistors exhibit when just the indium or indium-gallium film was applied.
  • the term "hot resistance” will be understood to refer to the maximum resistance of a positive temperature coefficient resistor above the Curie temperature thereof.
  • a reduction of the hot resistance of a positive temperature coefficient resistor decreases the high increase in resistance required at temperatures above the Curie temperature of the resistor. Accordingly, it would be highly desirable to avoid a reduction in the hot resistance of a resistor.
  • the invention provides a method of substantially eliminating any reduction in the hot resistance of a positive temperature coefficient resistor.
  • stabilization of the hot resistance of ceramic positive temperature coefficient resistors is attained by subjecting such resistors to heat treatment over a period of time ranging from 1 to 40 hours at a temperature in the range of 400° to 500° C. either during or after the application of contact coatings onto such resistors.
  • FIG. 1 is a graphical illustration comparing the resistance characteristics of a positive temperature coefficient resistor having an indium-gallium contact thereon and that of a similar resistor having a sintered silver contact;
  • FIG. 2 is a graphical illustration of the increase in hot resistance of positive temperature coefficient resistors after sintering silver thereon, as a function of temperature and time;
  • FIG. 3 is a graphical illustration of the relation between hot resistance and the sintering conditions.
  • the invention provides a method of stabilizing the hot resistance of ceramic positive temperature coefficient resistance and eliminating the reduction of the hot resistance of cold conductors (i.e., temperature sensitive resistors) having silver contacts on an indium or indium-gallium layer by subjecting such cold conductors to a heat treatment during or after the burning-in or stoving process.
  • cold conductors i.e., temperature sensitive resistors
  • the hot resistance of a ceramic positive temperature coefficient resistor composed of a barium titanate based ferroelectric material having a Perowskite structure and being appropriately doped to render it semiconductive and having non-blocking contact coatings thereon, which are predominantly composed of silver on a thin film of an indium material, such as indium or indium-gallium, is stabilized by subjecting such resistor to a heat treatment over a period of time ranging from 1 to 40 hours at temperatures in the range of 400° to 500° C., at least after the application of the contact coatings.
  • the heat treatment comprises subjecting positive temperature coefficient resistors to a heat treatment over a period of time ranging from 10 to 20 hours at a temperature in the range of 400° to 500° C. after application of the non-blocking contact coatings to the resistor.
  • Other embodiments of the invention comprise subjecting the positive temperature coefficient resistor to a heat treatment over a period of time ranging from 2 to 4 hours at a temperature in the range of 400° to 500° C. substantially simultaneously with the application of the non-blocking contact coatings to the resistor.
  • the invention also provides a ceramic positive temperature coefficient resistor composed of a barium titanate based ferroelectric material having a Perowskite structure which is doped so as to render it semiconductive, which resistor is provided with non-blocking contact coatings comprised predominantly of silver applied on a thin film of an indium material directly on the surface of the ferroelectric material which ceramic resistor is characterized by a stable hot resistance virtually equal to the hot resistance of a substantially similar resistor without silver on the contact coating thereof.
  • Positive temperature coefficient resistor discs composed of an antimony doped barium titanate compound having a Curie temperature of 120° C. and having a diameter of 8 mm and a thickness of 0.5 mm were provided in a known manner with an indium-gallium contact.
  • the resistance-temperature characteristic of these resistors were measured and the solid-line curve at FIG. 1 illustrates these results.
  • a commercially available silver preparation suitable for sintering was applied onto the indium-gallium film and heated, stoved or sintered for 12 to 15 minutes at 530° C.
  • the resistance-temperature characteristic of these resistors were measured and the broken-line curve at FIG. 1 illustrates the results.
  • the hot resistance of the silver-coated positive temperature coefficient resistance is less by a factor of more than 10 while the cold resistance remains unchanged in relation to that of the indium material-coated resistors.
  • FIG. 2 shows how the hot resistance, R H , of the positive temperature coefficient resistor increases as a function of time at different temperatures.
  • the ratio of the hot resistance R H , after heat treatment to the hot resistance, R Ho , after the silver sintering process, is shown on the ordinate of the graph of FIG. 2.
  • the broken-line in FIG. 2 illustrates the ratio R H /R Ho for indium-gallium coated positive temperature coefficient resistors.
  • an increase in hot resistance by a factor of 20 to 25 is attained, after a heat-treatment over a period of time ranging from 15 to 20 hours at temperatures in the range of 400° to 450° C.
  • a substantially identical increase in hot resistance is also noted after a heat-treatment of only 10 hours at a temperature of 500° C.
  • the invention provides a method of achieving virtually the heat resistance of a positive temperature coefficient resistor which has only been coated with pure indium-gallium.
  • FIG. 2 also illustrates that at temperatures below about 400° C., no appreciable increase in hot resistance is attained (i.e., see the curve for 300° C.). At temperatures above about 500° C., perceptible oxidation of the indium-gallium film takes place and this gives rise to high contact resistances.
  • FIG. 3 illustrates the ratio R H /R Ho as a function of time, t, using different heating temperatures as a parameter. As shown, after a heating time, t, of 3 to 4 hours at a temperature of 400° to 450° C., an increase in the hot resistance R H , by a factor of 20 to 25 is attained, thus virtually reaching the resistance value of the resistor with only an indium-gallium electrode (illustrated by the broken-line).
  • the heat-treatment of the invention eradicates oxygen gaps in the crystal lattice of the resistors, which may have developed during the silver application process as a consequence of a slight chemical reduction.
  • oxygen gaps may produce an additional conductivity and therefor function as a shunt, vis-a-vis the high ohmic grain boundaries, so that the hot resistance is substantially reduced.
  • the principles of the invention may be used to eradicate mechanical stresses from the body of a positive temperature coefficient resistor. As will be appreciated, mechanical stresses may impair the electrical properties of such resistors.
  • the resistance increase achieved by the principles of the invention are due to genuine changes in the conductivity of the ceramic.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Thermistors And Varistors (AREA)
  • Apparatuses And Processes For Manufacturing Resistors (AREA)
US05/478,855 1973-06-18 1974-06-13 Method of stabilizing the hot resistance of ceramic positive temperature coefficient resistors Expired - Lifetime US3934058A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DT2330908 1973-06-18
DE19732330908 DE2330908C3 (de) 1973-06-18 Verfahren zur Stabilisierung des HeiBwiderstandes von keramischen Kaltleitern

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US3934058A true US3934058A (en) 1976-01-20

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US (1) US3934058A (is")
JP (1) JPS5035697A (is")
AT (1) AT330306B (is")
BE (1) BE816494A (is")
FR (1) FR2233688A1 (is")
GB (1) GB1464422A (is")
LU (1) LU69220A1 (is")
NL (1) NL7408152A (is")

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4073971A (en) * 1973-07-31 1978-02-14 Nobuo Yasujima Process of manufacturing terminals of a heat-proof metallic thin film resistor
US4455744A (en) * 1979-09-04 1984-06-26 Vishay Intertechnology, Inc. Method of making a precision resistor with improved temperature characteristics
US5241741A (en) * 1991-07-12 1993-09-07 Daito Communication Apparatus Co., Ltd. Method of making a positive temperature coefficient device
US5316973A (en) * 1991-04-30 1994-05-31 Gte Control Devices Incorporated Method of making semiconducting ferroelectric PTCR devices
US20060258040A1 (en) * 2005-05-11 2006-11-16 Instrument Technology Research Center, National Applied Research Laboratories Microsensor with ferroelectric material and method for fabricating the same
US20190109067A1 (en) * 2016-07-04 2019-04-11 Denso Corporation Semiconductor chip and semiconductor device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59229803A (ja) * 1983-06-11 1984-12-24 秩父セメント株式会社 Ｐｔｃ　サ−ミスタの製造法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3037180A (en) * 1958-08-11 1962-05-29 Nat Lead Co N-type semiconductors
US3258434A (en) * 1962-08-01 1966-06-28 Gen Electric Semiconducting glass
US3449824A (en) * 1964-10-26 1969-06-17 Rca Corp Method for preparing a ferroelectric body and devices
US3754987A (en) * 1971-06-04 1973-08-28 Texas Instruments Inc Method of producing areas of relatively high electrical resistivity in dielectric substrates

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3037180A (en) * 1958-08-11 1962-05-29 Nat Lead Co N-type semiconductors
US3258434A (en) * 1962-08-01 1966-06-28 Gen Electric Semiconducting glass
US3449824A (en) * 1964-10-26 1969-06-17 Rca Corp Method for preparing a ferroelectric body and devices
US3754987A (en) * 1971-06-04 1973-08-28 Texas Instruments Inc Method of producing areas of relatively high electrical resistivity in dielectric substrates

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4073971A (en) * 1973-07-31 1978-02-14 Nobuo Yasujima Process of manufacturing terminals of a heat-proof metallic thin film resistor
US4455744A (en) * 1979-09-04 1984-06-26 Vishay Intertechnology, Inc. Method of making a precision resistor with improved temperature characteristics
US5316973A (en) * 1991-04-30 1994-05-31 Gte Control Devices Incorporated Method of making semiconducting ferroelectric PTCR devices
US5241741A (en) * 1991-07-12 1993-09-07 Daito Communication Apparatus Co., Ltd. Method of making a positive temperature coefficient device
US20060258040A1 (en) * 2005-05-11 2006-11-16 Instrument Technology Research Center, National Applied Research Laboratories Microsensor with ferroelectric material and method for fabricating the same
US7413912B2 (en) * 2005-05-11 2008-08-19 Instrument Technology Research Center, National Applied Research Laboratories Microsensor with ferroelectric material and method for fabricating the same
US20190109067A1 (en) * 2016-07-04 2019-04-11 Denso Corporation Semiconductor chip and semiconductor device
US10943847B2 (en) * 2016-07-04 2021-03-09 Mitsubishi Electric Corporation Semiconductor chip and semiconductor device

Also Published As

Publication number Publication date
BE816494A (fr) 1974-10-16
NL7408152A (is") 1974-12-20
GB1464422A (en) 1977-02-16
ATA247574A (de) 1975-09-15
DE2330908B2 (de) 1976-07-29
FR2233688A1 (is") 1975-01-10
AT330306B (de) 1976-06-25
DE2330908A1 (de) 1975-01-09
LU69220A1 (is") 1974-04-08
JPS5035697A (is") 1975-04-04

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